Download the free Reaper manual. Read the section on installing plugins.
Alternatively, Copy the plugin to wherever you keep your other plugins - mine I put in a directory I made in C:\ Prorams\VSTPlugins.
Open reaper and go to the Options/prefs menu.
There you will find a sub menu item for vst plugins. Click on it, re-scan your plugin directory and Reaper will pick up on and ue anything you put in the path you are scanning. DO OT put it in the reaperplugins folder, this is exclusively for use with the built-in plugins that come with reaper.
But if you didn't already, read the manual, watch any and all video tutorials you can find on here and on Youtube. Kenny Gioia is highly recommended. Some of his are free but he also does an excellent series on
www.groove3.com that you have to pay a little for.
It's all good